1. Field of the Invention
The present invention relates to a pressure sensor device that includes a temperature sensor contained in a common housing, and especially to such a pressure sensor device in which a response speed of the temperature sensor is improved.
2. Description of Related Art
Some examples of the pressure sensor device including a temperature sensor are disclosed in JP-A-2006-194682, JP-A-2006-194683 and JP-A-2005-274412. With reference to FIG. 5 attached hereto that shows an outline of a pressure sensor device disclosed in JP-A-2006-194682, a structure of a conventional pressure sensor device will be explained. A housing of the pressure sensor device 100 is composed of a resin head 10 and a resin pipe 30, both connected to each other. Terminals 11 for making electrical connections to an outside circuit are insert-molded in the resin head 10. A pressure sensor element 20 is mounted on a depressed portion 12 formed on the resin head 10 and electrically connected to one of the terminals 11.
The resin pipe 30 includes an upper end forming a pressure-detecting chamber 16 and a lower end 31 for introducing air, a pressure of which is to be detected. In the resin pipe 30, an air passage 31a and a space 31b for mounting a temperature sensor 40 are formed. The air passage 31a and the space 31b are separated from each other by a separator 32. A temperature sensor element 40 is disposed close to the lower end 31 and electrically connected to a connecting portion 23 through a lead wire 24. The connecting portion 23 is connected to one of the terminals 11. The lead wire 24 is supported in the space 31b with a resilient cushion member 25 made of a material such as resin.
As the temperature sensor element 40, a thermistor having a diameter of about 3 mm is used. The lead wire 24 is made of a metallic wire having a diameter about 0.5 mm. The lead wire 24 extends from the connecting portion 23 in the resin head 10 to a bottom portion of the resin pipe 30. The pressure sensor 100 is mounted on an intake manifold of an automotive engine to detect air pressure and temperature taken into the engine. An amount of air taken into the engine is calculated based on the detected pressure and temperature. The temperature sensor element 40 has to be positioned close to the lower open end 31 of the resin pipe so that it is exposed to the intake air. For this purpose, the temperature sensor element 40 has to be supported by a thick and strong lead wire 24. However, there is a problem that the thick lead wire reduces a response speed of the temperature sensor and is detrimental to making the sensor device compact.